Housings with electronic plug-in assemblies are typically integrated in control cabinets. The structural height of the housing must be as small as possible in relation to the inserted plug-in assemblies, so that the available space in the control cabinet is used optimally and costs related to the footprint of the control cabinet can be reduced.
However, due to the high density of electronic plug-in assemblies, problems arise with heating. The amount of heat dissipated by the plug-in assemblies has increased steadily due to higher packing densities and timing frequencies of the plug-in assemblies. Thus, increased cooling requirements are placed on systems and especially the housing for holding the plug-in assemblies.
In the field of telecommunications, particularly strong cooling is required because standards in the field of telecommunications applications permit heat dissipation of greater than 200 W for each plug-in assembly. The ATCA standard housing (Advanced Telecom Computing Architecture) developed by PICMG (PCI Industrial Computing Manufacture Group) typically provides space for 14-16 adjacent plug-in assemblies. The total amount of heat dissipation is thus approximately 3000 W. This heat must be effectively removed in order to prevent overheating and failure of the plug-in assemblies.
In order to optimally use the available space in the control cabinets, the individual housings have only relatively small spatial requirements for guiding the cooling air. This reduction in space for guiding cooling air stands diametrically opposed to the growing amount of heat dissipated and stricter cooling requirements.
In the state of the art, telecommunications systems are known in which several small fans are arranged underneath the component installation space of the plug-in assemblies and air is forced vertically upward along the plug-in assemblies. The cooling air is then discharged laterally from the housing, usually on the rear side, above the component installation space. Because the incoming cool air flows around the fans, their temperature load is low, which has a positive effect on their service life. However, the air conduction above the component installation space is less effective.
In other housings, axial fans are arranged above the plug-in assembly. In order to improve air conduction and prevent a blockage of air in the space above the component installation space, it is known to place the individual fans at an angle, so that the discharged air flows past the other fans. However, this arrangement often cannot be realized due to the given structural height of the housing. One example here is US 2003/0214785 A1. Another example for the arrangement and use of axial fans for cooling housings is known from U.S. Pat. No. 6,042,474.
Instead of axial fans, particularly, in housings for telecommunications applications, radial fans are often used that involve a structural 90°-deflection of the airflow. The radial fans arranged above the component installation space of the plug-in assemblies draw in air from below and discharge it laterally through the air outlet of the housing. One possibility for the effective cooling of such ATCA standard housings for telecommunications applications is known, for example, from EP 1 705 977. However, the use of radial fans is relatively expensive.